15 character limit?

Discussion in 'DNS Server' started by .:mmac:., Apr 1, 2005.

  1. .:mmac:.

    .:mmac:. Guest

    I have a win2k domain that due to my stupidity has more than 15
    characters in it's name. I notice that when I logon, the dialog only
    displays the first 15 characters in the domain listbox. Am I heading for
    trouble? the workstations a are a mix of win2k and XP with a single win98
    For a test I ran NSlookup and used the 15 character name as the domain
    and nothing could be found. SO I added a zone for that 15 character name,
    added all the machines and they resolve, but is that necessary? Will
    anything be limited to that 15 character name?
    .:mmac:., Apr 1, 2005
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  2. .:mmac:.

    Todd J Heron Guest

    This is not necessarily a problem, except that it generally confuses users
    and (new) administrators on such a network (unless this is only your small
    test network). The domain NetBIOS name can be completely different from the
    DNS name. For simplicity's sake, the DNS name is often simply the domain
    NetBIOS name with an extension added on such as .local or .com. The fact
    that it is cutting off at 15 characters is a NetBIOS (but not DNS)
    limitation. You have two choices. Either live with it or rename the
    domain. Keep in mind if you rename the domain this may impact legacy
    applications that look for the domain NetBIOS name as they open up or run
    their internal operations.
    Todd J Heron, Apr 1, 2005
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  3. .:mmac:.

    Herb Martin Guest

    You should not have trouble if there are NOT more than
    15 characters in the NetBIOS name -- the full DNS name
    can be longer.

    My personal rule is actually 14 characters (because there
    were/are some weird products out there that had problems
    with even 15 and even though 16 is the NetBIOS name limit
    the applications/systems use the final character always.)
    There should/must always be a 15 character or shorter
    NetBIOS version name of the domain.

    This is enforced at DCPromo of the first DC -- you may in
    fact have just truncated your netbios name version without
    realizing it.

    The default is the "left most label" of the DNS name IF IT
    Herb Martin, Apr 1, 2005
  4. Is that the AD NetBIOS domain name or the AD DNS domain name?

    The reason why I ask is if the DNS domain is a single label name is because
    you said you created a zone for that name. A domain name without .com, .net,
    ..mac, etc, is called a single label DNS name and that definitely WILL cause


    Please direct all replies ONLY to the Microsoft public newsgroups
    so all can benefit.

    This posting is provided "AS-IS" with no warranties or guarantees
    and confers no rights.

    Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
    Microsoft Windows MVP - Windows Server - Directory Services

    Paramount: What's up with taking Enterprise off the air??
    Infinite Diversities in Infinite Combinations.
    Ace Fekay [MVP], Apr 1, 2005
  5. .:mmac:.

    .:mmac:. Guest

    Yep, I'm confused all right.
    that must be what happened, it truncated automatically.
    How can I see if there are more than 15 in the netbios name if all that will
    be shown is the first 15?
    I think the netbios name (the shortened one) is what shows up in the logon
    dialog and the domain name (the full name) is only in DNS?
    I gotta wrap my head around this seemingly simple concept!
    .:mmac:., Apr 7, 2005
  6. .:mmac:.

    .:mmac:. Guest

    Hi Ace!
    I am having trouble seeing where the two names are used!
    the logon screen shows the 15 character name and dns uses the long one.
    which is which? I am logging onto an AD domain so why is the domain name
    shown only 15 characters?

    "Ace Fekay [MVP]"
    .:mmac:., Apr 7, 2005
  7. .:mmac:.

    Herb Martin Guest

    You can never set a "visible" NetBIOS name longer
    than 15 characters since the OS uses character position
    #16 for system purposes -- every NetBIOS name on the
    network is EXACTLY 16 characters long so only the
    first 15 are available for domains, computers, user names
    etc. (and in fact I would restrict it to 14 characters for
    true safety.)
    There will never be more than that -- if you use a longer
    DNS name it will be TRULY truncated -- this is NOT just
    a display issue. (The extra characters are gone.)
    Right. It used the DNS to pick the NetBIOS name by truncating
    it -- and since you didn't override it then "what you see is what
    you get."
    Herb Martin, Apr 8, 2005
  8. Hi Mike,

    The NetBIOS name is referred tothe legacy name. When you look in an AD's
    user account properties, Account tab, you can see the two different names.
    The first is the , which is called the UPN (Universal
    Principle Name) and is based on the AD's DNS domain name. When you login,
    you can type that whole thing in for the logon account and you will notice
    the domain name box on the bottom gray out.

    The second one is based the legacy NetBIOS name, the one you have to choose
    in the bottom domain name box. When you setup AD, we usually select the
    NetBIOS name to be the same name for the 2nd level portion of the DNS domain
    name. For "domain.com"'s NetBIOS name, I would choose 'DOMAIN" for the
    NetBIOS name. You can choose something different if you like for the NETBIOS
    name, but it cannot be more than 15 characters. If the DNS domain name's 2nd
    level name is more than 15 characters and you do not choose a different
    name, dcpromo will truncate it upon domain creation.

    The single label DNS domain name is an issue where one would choose "domain"
    (a single label DNS domain name without a hierarchy) for the DNS domain name
    instead of the proper format of "domain.com". If a single label name, it
    causes major problems with DNS.

    I hope that helps

    Ace Fekay [MVP], Apr 8, 2005
  9. .:mmac:.

    .:mmac:. Guest

    I gotta look into this.
    thanks, you've given me food for thought.
    .:mmac:., Apr 8, 2005
  10. .:mmac:.

    .:mmac:. Guest

    Two interesting points.
    my user logon name in the account tab is blank for all my users as is the
    box to the right.
    the user logon name (prewindows2000) shows the truncated name followed by a

    The single label name (truncated domain name ) in DNS exists but is one I
    recently created so see what the effect would be. I was hoping it would
    correct the intermittant failure of network places to proigate with machine
    names. But while I thought it worked, fron what I read here that should have
    made no difference at all so forgetting that perceived (wishful thinking?)
    result, I have seen no effect at all positive or negative. So I guess I can
    delete that zone?

    "Ace Fekay [MVP]"
    .:mmac:., Apr 8, 2005
  11. .:mmac:.

    Herb Martin Guest

    Failure of Net Places to allow browsing is a NetBIOS
    RESOLUTOIN problem.

    If you have multiple subnets (internal routers) then it is
    almost always due to a lack of WINS server or some
    other WINS server/client misconfiguration.

    1) NetBIOS must be enabled on machines.

    2) All clients must be set to the same WINS database
    by using the proper WINS server on their NIC->IP
    ->Advanced->WINS tab

    3) "Servers" are WINS CLIENTS TOO!!! (They must
    have the WINS servers set in IP properties)

    4) Multiple WINS servers must be replicated so as to
    have one WINS 'database'
    Herb Martin, Apr 9, 2005
  12. .:mmac:.

    .:mmac:. Guest

    Got it.
    In this situation I have ONE server only and no other subnets.
    The one server is DC, DNS,WINS, SQL, and everything else.
    based on what you say it should eb golden so there must be some other sort
    of issue that makes this happen.
    Thats why I was wondering about this whole issue. Everything seems to be
    right uet...
    I guess it's time to call some one in to exorsize the demons.
    .:mmac:., Apr 11, 2005
  13. .:mmac:.

    Herb Martin Guest

    No, it is almost certainly the failure to place the DNS
    and WINS server addresses on each and every client.

    Clients include Servers -- even the one with DNS and WINS.

    NIC->IP properties (and Advanced for WINS)
    No, it's time to find the misconfigured DNS/WINS clients --
    probably the including the Server itself (which is a name
    resolution client.)
    Herb Martin, Apr 11, 2005
  14. Yes, delete that zone. Not needed. As for network neighborhood, as Herb said
    that's NetBIOS based. If there are routers in between, use WINS to
    facilitate NetBIOS name resolution.

    Ace Fekay [MVP], Apr 11, 2005
  15. .:mmac:.

    .:mmac:. Guest

    OK I'll inspect every one.
    Does the add DNS suffix entries have any meaning in this context?
    .:mmac:., Apr 11, 2005
  16. .:mmac:.

    Herb Martin Guest


    DNS suffixes only affect what the client USER can type (unqualified
    names) which are resolved by trying the name specified AND
    each of the suffixes.
    Herb Martin, Apr 11, 2005
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